Vat dyeing of cellulose ethers and esters



var DYEING er CELLULQSEETHERQ AND ESTERS' Paul; A Studer, Milhurn, and Victor S. Salvin, Irvington, N J., assignors to .Celanse Corporation. of America,

New'YQ'rk; N.IY., a corporatlhh of Delaware N Drawing. Applicationl' 'Juhe: 2 1, "M52;

SeriaI'Not 294,917

17 Claims. (or. s- -ssy V This invention relates to the ldyeing of celluloseacetate United States Patefl' jQ or other organic derivative of cellulose, and more particularly to the dyeing of textile fabrics of cellulose acetate with vat *dyestufis't It is 'an object of our invention to-provide an improved proces's for dyeing cellulose acetate 'or othe'r 'orga'nic derivati've of cellulose with vatdyestuits."

'It is a JSu'rth'e'robject of our invention to provide a process for dyeing textil'efabrics ofcelliilose acetate or other organic esters of cellulose with vat dyestutfstogive good dyeingsi'under such conditions thatthere is no 'dang'er of sapon'ification of the cellulose ester and" no impairment Still another objectof our inventi'on is topr'ovide a process-i-for dyeing textile *fabricsof cellulose acetate or 1 other organic derivative of cellulose with vat dyestuffs to give level dyeings which have good. color value and which show no crocking.

Other "bbjects of this invention will appear'ffrom the following detailed description.'

ln th'e ushaP- application of vat dyestuffs to textile "materials; such as cotton the vat dyestufi. is first reduced or vatted in water by means of a reducing agent, such "as sodium hydrosulphite, and an alkaline material, such as sodium hydroxide, toproduce an aqueous solution of 'the soluble alkaline salt'rof- 'the leuco or reduced form of the vat dyestufi. This solution is applied to thevtextile material and the treated textile material is then subjected to oxidizing conditions, as by exposure to air, to convert the leuco salt into the oxidized insoluble form of the dyestufi. Afteroxidation, the dyed textile material is soured on "cellulose acetateor other organic derivative of cellulos'e textile materials, dyeings which are un1evel,'unreprjodilcible, of poor 'color'v'alue, and show heavy .crocking. This poor. dyeing takes place even 'thoughtthe vattacidd ispersions used are. clear, eX-tremelyfine and stable, show no precipitation on standing, and give 'perfectwtests on filterwpapen; It appears that the poor results are due-t0 the fact that the dye is deposited at thesurface-of the fiherin one form oranother andvdoes not penetrate adequately into the cellulose acetate fibers evenin the presence of a swelling agent.

The process of ourinvention .involvesthe application to cellulose acetate or other organic derivative of cellulose oii a dispersion ofwa vat acid in the presence of polyvinyl pyrrolidon'eand the oxidation of the vat acid on the celluloselderivative. We *have found that the introduction of the polyvinyl pyrrolidone results in dyeingsiwhich show practically no crockingiand .are'level, readilyrep'roduc'ible and of goodcolor value. The dye penetrates well into the fibers of celluloseacetate or other organicderivative of cellulose, even when ho swelling agent is present.

The results we obtain by the use of the combination of the dispersed vahacid and the polyvinyl pyrrolidone'are quite-surprisingin view of the known effects of polyvinyl pyrrolidone in. vat'dyeing cotton or regenerated cellulose materials. In the dyeing'of such materials polyvinyl pyrro'lidoneis usedas a stripping agent, in the presence of an alkalinereducing agent, to remove the'vat dye from the cotton or regenerated cellulose fibers. It has been postulated inthe prior art that this stripping action is due to a very powerful attraction between the dyestufii and the polyvinyl-pyrrolidone, the bond between the dyestuif and the polyvinyl. pyrrolidone being-much stronger than the attraction of 1 the cellulosefor the-dyestuft. The prior art has recognized that this powerful bond between the dye stuff and the polyvinyl pyrrolidone in the alkaline vat dyebath obviously operates against its use as a leveling assistant in the vat dyebath, so that thepolyvinyl pyrrolidone has been used in leveling-only finished vat dyeings which are uneven, in which case it operates because of its stripping action.

By the use of our new process we have obtained excellentdyeingswith a large number of vat dyestuifsgincluding'dyes of the indigoid, thioindigoid, violanthrone, pyranthrone and indanthrone types. Among the many vat dyes which we have tried with excellent results-are Jade Green C. I. 1 101; Helindon Brilliant Blue 4B C. I. 1184; Ahcovat Golden Yellow GK Pr. 29'1; Al1covat Brilliant Violet'4R C. I. 1104; Calcosol-Violet 6RD I. 1212; Ahcovat Orange RKS; Calcosol Fast Yellow; In'danthrene BrilliantYellow 3G; Ahcovat Yellow 4G8; Calcosol Pink FFD Pr. 109. I

The amount of polyvinyl'pyrr'olidone employed in the dyebaths of our-invention may be varied widely: Be-

45 sirably it may rangevfrom about.0.2 to 2 grams per liter of dyebath.

The aqueous dispersions of vat acids which we use may be made by any desired procedure. One method is to solubilizethe vat dyestufi by reducing it to the leuco form in an aqueous alkaline medium, followed by the addition of acid, such as acetic acid, in the' presence of a dispersing agent. If ydesired, the' resulting vat acid dispersion may be oxidized to produce a dispersion cf theoxidized dyestu'if, which dispersion maybe stored for a considerable period of timeand then converted, when needed; into a dispersion ofthe vat acid by direct reducti'on with a reducing agent such as 'zincsulfoxylate formaldedhydei It is desirable, particularly when darker shades arenecessary,to have present a swellingagent for the cellulose acetate orother organic derivative of cellulose material. Swellihg'agentssuch as 2-butoxy ethanol and the monobutyl ether'of diethylene glycol (Z-butoxyethoxYethanol), diacetone alcohol and triethyl phosphate may be present. The an'ro'untof swellingagent should preferably be 'belo'w that which causes delus'tering of the cellulose acetat'e or other organic derivative "of cellulose textile' m'aterial.

The swelling-agent may be added at any stage of thepreparation of the mixture, but for best results it should be added to the vat acid dispersion rather than to the vat mixture in alkaline form. I

In our improved dyeing process the dispersion of the vat acid containing polyvinyl pyrrolidone is applied at a pH of 4 to 7. Optimum results are obtained within the pH range of about 5 to 7. We prefer to use acetic acid to acidify the mixture, but are by no means restricted thereto. Examples of other suitable acids are formic, oxalic and citric acid.

The dispersion of the vat acid may also contain an added amine, such as hexamethylenediamine, cyclohexylamine, pyrrolidine or ethylene diamine. When the amine is present, the amount thereof should be such that the pH of the dispersion is not above 7, and is preferably in the range of pH 6 to 7.

In order to maintain the dispersion of the vat acid in the reduced state a reducing agent should be present. Preferably, this reducing agent should be one which will maintain a slightly acid dyebath in a reduced state for an extended period of time at an elevated temperature. Particularly desirable reducing agents for this purpose are zinc sulfoxylate formaldehyde Zn(HSO2,CH2O)2 and Hydrosulfite AW NaHSOz.CHzO.I-Iz0, especially at pH 4 to 6, and thiourea dioxide which is most suitable at pH above 6. Sodium hydrosulfite effects rapid reduction but does not maintain the dyebath in reduced condition for a long time at pH much below 7. 7

After the fabric leaves the dyebath, it may be rinsed and then oxidized. Any suitable oxidizing medium may be employed, such as hydrogen peroxide, sodium perborate or sodium nitrite acidified with sulfuric acid. The addition of an oxidizing agent to the swelling agent assists the oxidation. A hot soaping treatment is frequently advantageous in order to ensure that the shade of the dye is properly developed. A steaming treatment may be employed for this purpose in place of or in addition to the hot soaping treatment. The steaming treatment may also be applied before the oxidation.

The dispersion of the vat acid may be applied, if desired, by mechanical impregnation as by pad dyeing or printing. For such application, the dye liquid may be thickened in any convenient way, for example with a gum, such as gum tragacanth, or a water-soluble alkyl cellulose, e. g. methyl cellulose or hydroxyethyl cellulose. Following the impregnation, as by pad dyeing or printing, the material may be dried, steamed, under pressure if desired, washed and oxidized.

In order further to illustrate my invention, but without being limited thereto, the following examples are given:

Example I 2.00 parts by weight of Jade Green C. I. 1101, 12,12- dimethoxy dibenzanthrone, are dispersed, by stirring, in 1000 parts by weight of water containing 5 parts by weight of Peregal ST, which is a 30% solution of polyvinyl pyrrolidone in water, having a specific gravity of about 1.04. Then 22 parts by Weight of a 10% solution of sodium hydroxide in water and 2 parts by weight of sodium hydrosulfite are added and the mixture heated to 50-60 C. for l-15 minutes to completely reduce the dye to the sodium leuco compound. To the resulting mixture are added rapidly, with stirring 4,000 parts by weight of water containing 3 parts by weight of glacial acetic acid. This forms a dispersion of the vat acid. 10 parts by weight of zinc sulfoxylate formaldehyde Zn(I-ISOz,CHzO)2 and 90 parts by weight of Z-butoxy ethanol are added to the filtered dispersion, to produce a dyebath having a pH in the range of 4.5-5.5. This dyebath is heated to 8085 C. and agitated. 100 parts by weight of cellulose acetate textile fabric are immersed in the hot agitated dyebath for 2 hours, after which the dyed fabric is rinsed in lukewarm water and oxidized by immersion in an aqueous bath containing grams per liter of sodium perborate. After oxidation, the dye fabric is soaped for 20 minutes at 7080 C. with an aqueous solution containing 1.5 grams per liter of green soap. The fabric is colored a full, level, bluish green shade, which shows practically no crocking, and has a good band.

Example II Example I is repeated with the exception that in place of the Peregal ST there is substituted one of the following dispersing agents: (a) Tamol N, a sodium salt of a condensed aryl sulfonic acid, made by condensing naphthalene sulfonic acid with formaldehyde; (b) Dispersol VL, an ethylene oxide condensation product of a long chain fatty alcohol, or (c) Sandopan TN, a synergistic mixture of anionic and nonionic compounds. In each case the vat acid dispersion is fine, clear and stable. When a drop of each dispersion is placed on filter paper and allowed to spread through the paper, the outside of the ring formed by the spreading is the same shade as the center, where the drop was placed originally. However, the dyeing on cellulose acetate is poor in that it is not level, not reproducible, and shows heavy crocking. The dyestutf forms a layer on the fiber surface. The same results are obtained when the amount of each dispersing agent is increased fourfold.

Example III Example I is repeated with the exception that in place of the Peregal ST there is substituted one of the following dispersing agents: (a) Triton X-100, an alkyl aryl polyether alcohol; (12) Tinegal CV, a quaternary ammonium compound; (c) Nonisol-lOO, a polyoxyalkylene ester. In each case the vat acid dispersion is fine, clear, and stable and gives perfect results when tested on filter paper in the manner described in Example II. The dyeing on cellulose acetate in the dyebath appears to be very heavy. However, on rinsing in lukewarm water the dyestuff is removed almost completely from the fiber in each case. The same results are obtained when the amount of each of these dispersing agents is increased fourfold.

Example IV Example I is repeated except that Calcosol Pink FFD Pr. 109 is substituted for the Jade Green dyestuff. 'Ihe dyed fabric is colored a full, level pink shade, which shows practically no crocking and which has good light fastness.

Example V Examples II (a), (b), (c) and III (a), (b) and (c) are repeated except that Calcosol Pink FFD is substituted for the Jade Green. The use of this dye does not improve the results in any manner.

Example VI Example I is repeated except that the 90 parts of 2- butoxy ethanol are replaced by 65 parts of diethylene glycol monobutyl ether. Similar excellent results are obtained.

Example VII Example I is repeated, except that the Z-butoxy ethanol is omitted. The fabric is colored a medium, level, bluish green shade which shows practically no crocking.

Example VIII A dyebath is prepared from 0.4 gram per liter of Jade Green C. I. 1101, 1 gram per liter of Peregal St, 1 gram per liter of hexamethylene diamine, and 2 grams .per liter of sodium hydrosulfite by adding the vat dye to the aqueous solution, at 40 C., containing the Peregal ST and hexamethylene diamine, and then adding the sodium hydrosulfite and effecting reduction by heating to C. 500 parts of this dyebath, the pH of which is adjusted to 6.5 to 7, are used to dye 10 parts by weight of cellulose acetate textile fabric for two hours at 80 C. While agitating the dyebath, after which the dyed fabric is rinsed in T.5 lukewarm water and oxidized by sodium perborate. After oxidation, the dyed fabric is soaped. The fabric is colored a medium,';level,,,neat, appearing, bluish green s hade which shows practically, no crogking and has a good hand. i

- Exampl I Example XIII is repeated with the exception thatthe dye-bath also contains butoxyethanol, in a concentration of cc, per liter of dyebath. The dyed fabric is similar. to that of Example VIII but has a pronounced heavier shade.

While we have disclosed our invention more particularly in connection with the coloring of cellulose acetate fibers, it is equally applicable to the coloring of other materials which have a basis of other organic derivatives of cellulose. Examples of such other organic derivative of cellulose are cellulose esters, such as cellulose propionate, cellulose butyrate, cellulose acetate propionate and cellulose acetate butyrate and cellulose ethers such as ethyl cellulose and benzyl cellulose. The process can be applied to the organic derivatives of cellulose in the form of continuous filament yarns, or fabrics containing them, staple fiber products such as loose staple fiber, rovings, yarns or fabrics, or to self-supporting films.

Our dyeing process may be carried out over a wide range of temperatures. We prefer, however, to conduct the dyeing at a temperature within the range of about 70 to 95 C.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for the coloration of organic derivative of cellulose material, selected from the group consisting of cellulose esters and cellulose ethers, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion contains polyvinyl pyrrolidone and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

2. Process for the coloration of cellulose acetate material, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion contains polyvinyl pyrrolidone and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

3. Process for the coloration of organic derivative of cellulose material, selected from the group consisting of cellulose esters and cellulose ethers, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion contains polyvinyl pyrrolidone and a swelling agent for the organic derivative of cellulose and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

4. Process for the coloration of cellulose acetate material, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion con tains polyvinyl pyrrolidone and a swelling agent for the cellulose acetate and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

5. Process for the coloration of organic derivative of cellulose material, selected from the group consisting of cellulose esters and cellulose ethers, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion contains polyvinyl pyrrolidone and a glycol ether swelling agent for the organic derivative of cellulose and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

6. Process for the coloration of cellulose acetate material, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion contains polyvinyl pyrrolidone and a glycol ether swelling agent for the cellulose acetate and at a pH of 4 to 7, and then oxidizing said vat acid on said material.

7. Process for the coloration of organic derivative of cellulose material, selected from thegroupconsisting of cellulose esters and cellulose ethers, which Q IP iSes applying to said material astable aqueousdispersion of a aaqueousdispersion of a vat acid, which dispersion contains polyvinyl pyrrolidone and a reducing agent and has a. .pI-I,of 4. to 7, and then oxidizing said vat,acid ,onsaid material.

9. Process for the coloration of organic derivative of cellulose material, selected from the group consisting of cellulose esters and cellulose ethers, which comprises applying to said material a stable aqueous dispersion of a vat acid which dispersion contains polyvinyl pyrrolidone, a reducing agent and a glycol ether swelling agent for the organic derivative of cellulose and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

10. Process for the coloration of cellulose acetate material, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion contains polyvinyl pyrrolidone, a reducing agent and a glycol ether swelling agent for the cellulose acetate and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

11. Process for the coloration of textile material having a basis of an organic derivative of cellulose, selected from the group consisting of cellulose ethers and cellulose esters, which comprises applying to said textile material a stable aqueous dispersion of a vat acid which dispersion contains polyvinyl pyrrolidone, a reducing agent and a glycol ether swelling agent for the cellulose acetate and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

12. Process for the coloration of cellulose acetate textile material, which comprises applying to said material a stable aqueous dispersion of a vat acid which dispersion contains polyvinyl pyrrolidone, a reducing agent and a glycol ether swelling agent for the cellulose acetate and has a pH of 4 to 7, and then oxidizing said vat acid on said material.

13. Process for the coloration of cellulose acetate textile material, which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion is at a temperature of about 70 to C. and a pH of 4.5 to 5.5 and contains polyvinyl pyrrolidone, a swelling agent for the cellulose acetate selected from the group consisting of 2-butoxy ethanol and Z-butoxy-ethoxy ethanol and a reducing agent selected from the group consisting of zinc sulfoxylate formaldehyde and sodium sulfoxylate formaldehyde, and then oxidizing said vat acid on said material.

14. Process for the coloration of cellulose acetate textile material, which comprises applying to said material a stable aqueous dispersion of the vat acid of 12,12 dimethoxy dibenzanthrone, which dispersion is at a temperature of about 70 to 95 C. and a pH of 4.5 to 5.5 and contains polyvinyl pyrrolidone, a swelling agent for the cellulose acetate selected from the group consisting of Z-butoxy ethanol and 2-butoxyethoxy ethanol and a reducing agent selected from the group consisting of zinc sulfoxylate formaldehyde and sodium sulfoxylate formaldehyde, and then oxidizing said vat acid on said material.

15. Process for the coloration of cellulose acetate textile material which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion is at a pH of not above 7 and contains polyvinyl pyrrolidone and an amine, and then oxidizing said vat acid on said material.

16. Process for the coloration of cellulose acetate textile material which comprises applying to said material a stable aqueous dispersion of a vat acid, which dispersion is at a pH of about 6.5 to 7 and contains polyvinyl pyrrol- 7 Y 8 idone and hexamethylene diamine, and then oxdizing FOREIGN PATENTS said vat acid on said material. 5 5 Belgium Apr 14, 1951 17. A stable aqueous dispersion of a vat acid, said dispersion containing polyvinyl pyrrolidone and having a pH of 4 to 7. 5

OTHER REFERENCES Modern Plastics for November 1945, pages 157 to 161, 212, 214, 216 and 218.

American Dyestuff Reporter for February 1, 1954, pages P72-P75,

References Cited the file of this patent UNITED STATES PATENTS 1,900,172 Ellis Mar. 7, 1933 10 2,335,454 Schuster Nov. 30, 1945 2,524,073 Olpin Oct. 3, 1950 kt. tuna... 

1.PROCESS FOR THE COLORATION OF ORGANIC DERIVATIVE OFF CELLULOSE MATERIAL, SELECTED FROM THE GROUP CONSISTING OF CELLULOSE ESTERS AND CELLULOSE ETHERS, WHICH COMPRISES APPLYING TO SAID MATERIAL A STABLE AQUEOUS DISPERSION OF A VAT ACID, WHICH DISPERSION CONTAINS POLYVINYL PYRROLIDONE AND HAS A PH OF 4 TO 7, AND THEN OXIDIZING SAID VAT ACIDD ON SAID MATERIAL. 